Whoops, just read the topic title. (found the thread with a search)
I get the errors when Unity loads and they do not go away.
Just trying to keep my report accurate, not complaining.
:)

The actual error is:
Serialization depth limit exceeded at 'ShaderForge::SF_PreviewSettings'. There may be an object composition cycle in one or more of your serialized classes.
UnityEditorInternal.InternalEditorUtility:LoadSerializedFileAndForget(String)
UnityEditor.WindowLayout:LoadWindowLayout(String, Boolean)

Getting the same here.
Unity version (restricted).
Keeps SF from launching.